rebuild fuel selector valve
 

looks like I am going to need a fuel selector valve rebuilt. who does these for 337? (I haven't had chance to call McFarlane yet; I see they rebuild others.)

If it’s only leaking then it’s easy to replace the cork seal. But good luck getting that part. However, getting a sheet of cork and making the gasket is cheap and easy.

It's not providing a positive cut off of fuel flow. Wish it was easy as just needing cork gasket. Internals will need to be serviced. Are there any flexible rubber/plastic life limited internal parts? Is there a service kit?

I just went through this. The issue of leaking past the valve is from the little balls not sealing on the seats. The selector valve has a small well in it that can collect water. I think this contributes to the problem. The ball is held against the seat with a spring that is likely rusted. There will also be some rust on the seat that is causing your leak-past. You can remove the valve and see the ball/seat assembly. Don't remove the little clips that hold in the spring. They seem to be impossible to find. If a replacement clip/retainer was available this project would be pretty easy. I was only able to find one guy that was willing to look at them. He wanted a fortune and was a bit on the grumpy side.

I had one guy that thought removing the spring and ball and re-cutting the seat was the answer. I sent him one of my valves. It just sat on his desk for two months. On close inspection the seat was not pitted it appears to have surface rust that would likely clean up.

I think an ultrasonic cleaner would be a good start.

I found a pair of used valves that were not leaking.

Dave

Has anyone used B & S in Wichita lately?

I have been studying the valve drawings and come to the same conclusion myself about either corrosion (most likely) or some grit stuck in the ball/seat area. Also, been doing some research and B&S in Wichita is on my call list.

I have one of the old valves on the shelf. I'll take some pictures so you can plan your attack.

Dave

sounds great. surely there must be a matching internal c clip somewhere (I've been shopping internal c clip assortments-a kit with various assorted sizes very affordable) or if part is serviceable, clean things up and reuse.

There is! It's this little self-destructing thing that springs itself out of position once removed.

Dave

I dug out the old fuel selector valve. I have no recollection of how to attach a picture so I'm attaching several pictures. My computer has a .020" diameter thumbnail of the picture which is useless. Unfortunately I don't know how to add any descriptions to the pictures.

Here is a picture of the o-ring that sits on the shaft of the selector lever. This could be a source of leakage.

oh my goodness. that internal clip that holds the spring does look like it will be a problem. I wonder if an internal c-clip would work in it's place.

I will measure the thickness of it tomorrow. I don't have the right caliper to measure the inside groove diameter where it seats. One thing I would encourage is to take pictures and mark where the tubes go before you remove it.

Dave

additional info?
 

I was wondering if there was any follow up to this posting. I got to fly my skymaster for the very first time today.....and what a machine these things are!!!! What I found out was that when we were flying on the main tanks, the front engine would also pull fuel from the aux tank. 2.5 hours of flying time used 8 gallons out of the left aux tank. I moved the selector valve around a bunch of times to see if there was something stuck in it that could get worked out, but used about the same out of the aux tank on the next 2.5 hour flight. I am thinking the balls and seats have corrosion on them as was shown in the pictures in the post. I didn't want to have my mechanic rip it apart until he was certain he could replace those clips if one were to be broken or lost in the process.

Also, in the post below there is mention of B and S in Wichita. Did you ever reach out to them regarding rebuilding the valve? Just trying to wrap my head around all the options.

Thanks much guys!!!

Rigging
 

Tom,
I am not saying that it could not be some internal corrosion or problem in the valve, but if you have not verified, just double check the rigging of the valve. One small panel on at the wing root and a mirror, and you can verify that the valve is in the detents and rigged properly.
Jeff